diversity of life - classification and...
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Diversity of Life - Classification and Phylogeny
Classification
Classification v. Taxonomy
Classification• the systematic grouping of entities into categories
Taxonomy• the science of describing, naming and classifying
organisms
Diversity of Life - Classification and Phylogeny
Classification
Binomial name• two-word naming system (Carolus Linnaeus)
• First part is the genus (genera, plural)Second part is the species
written: Genus species or Genus speciesex. Felis catus (domestic cat)
Diversity of Life - Classification and Phylogeny
Hierachical classification• based on the grouping of related objects or description
of objects
Kingdom
Phylum
ClassOrder
FamiliesGenus
species
Broadcategory
Specificcategory
King
Philip
Can
Order
Families
Grow
Spinach
Diversity of Life - Classification and Phylogeny
Phylogeny
• the evolutionary history of a species or a group of relatedspecies.
Phylogenetic tree
• a branching diagram that represents a hypothesis aboutevolutionary relationships among organisms.
Diversity of Life - Classification and Phylogeny
Two systems are used to classify organisms:
Traditional (Aristotelian) analysis• Classification system based on similarities and differences
showing increasing complexity.
(Reptilia) (Aves) Lizards Snakes Crocodiles Birds - flight
common ancestor
Diversity of Life - Classification and Phylogeny
Cladistic analysis• Classification system based on evolutionary relationships
Lizards Snakes Crocodiles Birds
common ancestor
Diversity of Life - Arranging Life
Arranging Life
• remember that phylogenetic trees are hypotheses aboutevolutionary history
• they are always being revised or even rejected• classification is a work in progress
Two-kingdom system• life sub-divided into either plant or animals
Diversity of Life - Arranging Life
Five-kingdom system (Whittaker, 1969)
Monera Protista Plantae Fungi Animalia
earlyorganism
Diversity of Life - Arranging Life
Three-domain system• alternative system based on molecular and cladistical analysis
Bacteria Archaea Eukarya
earlyorganism
Diversity of Life - Arranging Life
Changing view of biodiversity
Monera Protista Plantae Fungi Animalia
BacteriaArchaea Eukarya
BacteriaArchaea Eukarya
Diversity of Life - Prokaryotes
Prokaryotes
Found everywhere there is life:
• inhabiting fertile soils, dead organisms• conditions from extreme cold --> extreme hot;
from extremely acidic --> extremely alkaline• inhabit humans (mouths, intestines)• outnumber all eukaryotes combined
Diversity of Life - Prokaryotes
Cellular organization (prokaryotes v. eukaryotes)
Prokaryotes Eukaryotes
No true nucleus Membrane-bound nucleus
Cell organelles absent Golgi apparatus, endoplasmic
reticulum, lysosomes,
mitochodria, chloroplasts present
Diversity of Life - Prokaryotes
This difference in cellular organization divides Prokaryotes andEukaryotes in the Five-kingdom system.
Monera Protista Plantae Fungi Animalia
earlyorganism
eukaryotesprokaryotes
Diversity of Life - Prokaryote evolution
Identification of two major branches of prokaryotic evolution: Bacteria and Archaea
Bacteria Archaea Eukarya
earlyorganism
similiar in:
• prokaryotic cellorganization
differ in:
• structure, biochemistryand physiology
Archaea may be more related to eukaryotes than bacteria
Diversity of Life - Prokaryote evolution
Comparison of the Three Domains of LifeCharacteristic Bacteria Archaea EukaryaNuclear envelope No No YesMembrane-
enclosed organellesNo No Yes
Peptidoglycan in
cell wallYes No No
Membrane lipids Unbranched
hydrocarbons
Some branched
hydrocarbons
Unbranched
hydrocarbons
RNA polymersase 1 kind several kinds several kinds
amino acid start of
protein synthesis
Formyl-
methionine
Methionine Methionine
Introns No Some YesAntibiotic
responsesYes No No
Histones No Yes YesCircular
chromosomesYes Yes No
growth at 100+oC No Some No
Diversity of Life - Prokaryotes
Bacteria
• found in soil, water, animal digestive tracks, etc.
• nutrition (fuel to drive cellular processes)– light energy (phototrophism)– organic/inorganic energy (chemotrophism)
Diversity of Life - Prokaryotes
Archaea (archaios = ancient)
• anaerobes• most species inhabit extreme environments
(extremophiles)
halophiles - require salt for growththermophiles - live near deep-sea thermal vents,
temps. >100oCacidophiles - enjoy acidic conditions
Diversity of Life - Prokaryote Structure and Function
Structure
• identification by cell shapeRound - Coccus
(pl. Cocci)
Rod - Bacillus
(pl. Bacilli)
Spiral - Spirillum
(pl. Spirilla)
Ex: Staphylococcus sp. Ex: Escherichia coli Ex: Streptomyecin sp.
Bacteria images by Dennis Knunkle
Diversity of Life - Prokaryote Structure and Function
Structure
• microscopic• unicellular
• motile (flagella)
Diversity of Life - Prokaryote Structure and Function
Reproduction
Binary Fission• asexual reproduction (creation of offspring by a single parent
without a sperm and egg)• parent organism divides into 2 individuals of about the same
size
Diversity of Life - Prokaryote Structure and Function
Reproduction
• exhibit exponential growth
• limiting factors: nutrients, space and metabolic wastes
population
size
time
Diversity of Life - Prokaryote Nutrition
Prokaryote Nutrition
nutrition - method by which an organism obtains resources for synthesizing organic compounds
• energy• carbon source
Energy sources Carbon sourceslight organic compounds
(containing carbon)
chemicals inorganic compound
Diversity of Life - Prokaryote Nutrition
Four major modes of nutrition are classified according tothese categories:
Photoautotrophs (photo = light; auto = self; troph = food)
• photosynthetic organisms that(1) use light energy to(2) synthesize organic compounds from CO2
• examples: cyanobacteria, algae, plants
Diversity of Life - Prokaryote Nutrition
Four major modes of nutrition are classified according to thesecategories:
Chemoautotrophs (chemo = chemical; auto = self; troph = food)
• organisms that(1) extract energy from inorganic compounds (H2S or NH3) to(2) synthesize organic compounds from CO2
• examples: prokaryotes living near deep-sea hot water vent
Diversity of Life - Prokaryote Nutrition
Four major modes of nutrition are classified accordingto these categories:
Photoheterotrophs (photo = light; hetero = other; troph = food)
• organisms that(1) use light energy to generate ATP but(2) must obtain carbon sources from outside organic forms
Diversity of Life - Prokaryote Nutrition
Four major modes of nutrition are classified accordingto these categories:
Chemoheterotrophs
• organisms that must consume molecules for both energyand carbon
• examples: some prokaryotes, protists and plants all fungi and animals
Diversity of Life - Protista
Protists
• eukaryotic• probably evolved through endosymbiosis
Bacteria Archaea Eukarya
earlyorganism
Protista Plantae Fungi Animalia
eukaryotes
prokaryotes
Diversity of Life - Protista
Protists
• simplest eukaryotic organism• complex on the cellular level
• most unicellular (but some live in colonies)Eukarya
Protista Plantae Fungi Animalia
Diversity of Life - Protista
Protists
Four major categories:
• Protozoans• Slime Molds• Unicellular Algae• Multicellular Algae
Eukarya
Protista Plantae Fungi Animalia
Diversity of Life - Protista
Protozoans
• nutrition: ingest food/ nutrients• habitat: watery environments
• classified by means of locomotion:FlagellatesCiliatesAmoebas
Diversity of Life - Protozoans
Flagellates
• move by means of one or more flagella (long appendage)• most are free-living (non-parasitic)
• example: Euglena sp.
Diversity of Life - Protozoans
Ciliates
• use cilia (short appendages) to move and feed• most are free-living
• example: Paramecium sp.
Diversity of Life - Protozoans
Amoebas
• use pseudopodia (temporary extension of the cell) formovement and feeding (phagocytosis)
• example: Amoeba proteus
Diversity of Life - Protists
Slime Molds
• filamentous bodies (resembling fungi, but don’t confusethem)
• pseudopodium for movement and feeding• decomposers
Diversity of Life - Protists
Unicellular Algae
• Photosynthetic
• many are components ofplankton(organisms drifting near surfaceof lakes or oceans)
• planktonic algae are calledphytoplankton (phyto = plant)
• primary producers in freshwaterand marine ecosystems
Diversity of Life - Unicellular Algae
Dinoflagellates
• unicellular• biflagellates (two whirling flagella)• aquatic
Ecological importance:• red tides
- coastal water discoloration by a bloomof red dinoflagellates- some red tide dinoflagellates producetoxins
Diversity of Life - Unicellular Algae
Diatoms
• unicellular• exoskeleton (contains silicon) composed of 2 halves
Diversity of Life - Unicellular Algae
Green Algae
• unicellular (some colonial)• inhabit freshwater lakes and ponds• most closely related to green plants
• example: Volvox
Diversity of Life - Protista
Multicellular
Seaweeds
• large, multicellular marinealgae
• similarity to true plants is anexample of convergentevolution
Diversity of Life - Plantae
What is a Plant?
• multicellular eukaryotes• terrestrial• synthesizes organic molecules by photosynthesis
CO2 H2O Glucose O2
Light energy
Eukarya
Protista Plantae Fungi Animalia
Diversity of Life - Plantae
Evolution to Land
• green algae are most closely related toplants
• molecular research shows that themulticellular, green algae (charophytes)is the closest relative to plants
• gradual accumulation of terrestrialadaptations
Diversity of Life - Plant Evolution
Terrestrial Adaptation
In the water ... all resources a plant needs are found all around
On land ... these resources are found in two different places
• light and CO2 available above ground• water and mineral nutrients are mainly in the soil
So ... some adaptations were needed for plants to exist on land
Diversity of Life - Plant adaptation to land
Structural Adaptations
Leaves - main photosynthetic organs• exchange of gases (CO2 / O2) through pores on the
leaf’s surface called stomata• cuticle (waxy layer) reduces water loss
Stems• support for plant• lignin-rich cell walls
Diversity of Life - Plant adaptation to land
Structural Adaptations
Roots• anchorage• absorption of water and minerial
Vascular Tissues• transport of vital materials between organs• system of tube-shaped cells
Diversity of Life - Plant Evolution
Plant Diversity
(1) Origin of plants --->
(2) Vascular plants --->
(3) Seeded plants --->
(4) Flowering plants --->
Bryophytes (mosses)
Ferns
Gymnosperms (conifers)
Angiosperms
Diversity of Life - Fungi
Fungi
• eukaryotes• mostly multicellular• more closely related to animals than to plants
• heterotrophs- acquire nutrients by absorption- secret enzymes that breakdown food
Eukarya
Protista Plantae Fungi Animalia
Diversity of Life - Fungi
Fungi Structure
• adapted for the purpose ofabsorbing nutrient
• bodies constructed of thread-liketubular structures called hyphae
• hyphae forms a feeding networkcalled the mycelium
• most of these structures areunderground
Diversity of Life - Fungi
Ecological Roles
• decomposers• recycle chemical elements
back into the environment
Diversity of Life
Calendar of Geological TimeCalendar of Geological Time (1 day = 150 million years)
11 2 3 4 5 6 7 2 3 4 5 6 7 88 9 9 1010 11 12 13 14 11 12 13 14
15 16 17 18 19 20 2115 16 17 18 19 20 2122 23 22 23 2424 25 26 27 25 26 27 28282929 3030
1: The origin of the Earth 1: The origin of the Earth 8: Prokaryote cells 8: Prokaryote cells10: Oldest fossils - bacteria and blue-green algae10: Oldest fossils - bacteria and blue-green algae24: First eukaryotic cells24: First eukaryotic cells28: First land plants28: First land plants29: Gymnosperms29: Gymnosperms30: Angiosperms; humans30: Angiosperms; humans